热活化焙烧—稀硫酸浸出贵州某煤矸石中的锂与铝OA

To achieve the high-value comprehensive utilization of coal gangue andprovide theoretical basis and technical support for its recycling,this investigation focuses on coal gangue from a coal mine in western Guizhou,China.Based on the occurrence characteristics of lithium and aluminum in the coal gangue,the leaching behaviors of lithium and aluminum was explored.A process involving thermal activation roasting followed by dilute sulfuric acid leaching was proposed.The effects of roasting temperature,roasting time,liquid-to-solid ratio,sulfuric acid concentration,leaching temperature,and leaching time on the leaching rates of lithium and aluminum were investigated.Furthermore,the mechanism of lithium and aluminum leaching was discussed.The unreacted shrinking core model was applied to analyze the kinetics of the synergistic leaching process.The results show that under the optimal conditions(roasting temperature of 500℃,roasting time of 150 min,liquid-to-solid ratio of 4∶1,sulfuric acid concentration of 15%,leaching temperature of 80℃,and leaching time of 90 min),the leaching rates of lithium and aluminum reach 92.80%and 85.26%,respectively.After roasting at 500℃,the kaolinite in the coal gangue transformed into disordered metakaolinite,enhancing its reactivity.In the strongly acidic environment provided by sulfuric acid,metakaolinite decomposes,gradually forming soluble aluminum sulfate and lithium sulfate,which enter the solution.The synergistic leaching process of lithium and aluminum is controlled by chemical reactions,with activation energies of 36.97 kJ/mol and 66.11 kJ/mol,respectively.